Enzymatic replication of E. coli chromosomal origin is bidirectional.

A soluble enzyme system has been discovered which specifically recognizes and replicates plasmids containing the Escherichia coli chromosomal origin, oriC. Electron microscopy has shown that plasmid replication begins at or near oriC from which it progresses bidirectionally to completion. Control of initiation of a cycle of chromosomal replication and mechanisms of priming and fork movement can now be explored using this system.